Portable devices that employ batteries, such as handheld cell phones, Internet appliances, personal organizers, point of sale (POS) terminals, portable computing devices and any other portable devices are increasingly using small removable accessories which are typically as small as a parent device to which they connect. For example, cell phones are proposed that employ card reader devices to allow a user to insert a credit card, smart card, or other information input devices into the cell phone to create smart card enabled telephone appliances, Internet appliances, portable ATM devices, and a litany of other compact portable products. Such small handheld devices typically require compact connectors to electrically and mechanically interconnect differing subsystems or components.
Accordingly, removable accessories typically must be connected to a mother board or other electrical circuitry in another part of the parent device. A problem arises when such accessories are to be integrated in small handheld devices. Batteries, which are typically used to provide power to, for example, cell phone circuitry or circuitry of a POS terminal, can be expensive items and can also take up large amounts of volume of a parent device or accessory device.
Batteries usually are one of the largest components of the hand held device. In addition, it is desirable to maximize battery storage areas since typically larger batteries can provide longer battery life for the parent device and/or accessory device. Conventional cell phones, for example, have battery covers that do not house a battery, but which merely cover the primary battery that is located in the body of the parent device. One example is a Motorola Inc. model number P7389 GSM Tri-band cell phone distributed from Motorola Inc., Harvard, IL, USA. A push button latch allows a user to attach or remove the battery cover to replace the primary battery in the parent device when needed. However, such battery covers do not typically include accessory devices, nor do they include electrical connection between the battery cover and a circuit in the parent housing.
With respect to a card reading accessory, one solution has been to redesign the battery compartment for the parent device and redesign the battery itself to accommodate the addition of an accessory component. For example, one design combines the accessory, such as a card reader, with an integrated battery in an integral accessory module, so that a user needs to purchase the entire accessory module when the accessory battery needs to be replaced. The accessory battery usually replaces the primary battery used by the parent device. In order to provide connection of electrical circuits including signaling busses, power and ground lines and other signaling lines between the accessory and parent circuitry, flexible circuits are typically added and designed to wrap around the accessory battery and electrically connect a circuit board in the accessory device with a circuit board in the parent device through a contact interface. These flexible circuits and connector interfaces add cost, take up additional volume and can reduce reliability. They also can increase the size of the accessory device and/or the parent device.
Alternatively, accessory devices are sometimes attached to existing cell phones and other electronic appliances through a base plug typically located, for example, at the base of a parent device housing. Base plugs are typically used to allow an external power connection to recharge the battery. For example, car lighters and conventional outlets can be used to recharge a battery through the base plug. In addition, other accessories such as microphones, speakers and other accessories may also be coupled to the base plug. Typical larger accessories, however, slide over the battery cover and obtain their power from the base plug. Such accessories typically overhang the profile of the parent housing thus making the parent device unnecessarily longer. Attaching in this fashion may cover the base plug. An additional base plug may have to be added in the accessory device to provide access to the primary device. This can increase cost. A further problem arises. Card readers and other devices that communicate highly proprietary information need to comply with tamper evidence standards.
For example, portable devices and nonportable devices typically need to be designed in such a way that if the device is tampered with, such tampering can be recognized readily. With credit card reading devices attached to cell phones or other appliances, financial transactions may require the device to send confidential credit card information and bank account information. Such devices should not typically allow access through external plugs so that a potential hacker can obtain the confidential information. Accordingly, base plugs should not typically provide outside access if they are coupled to a card reading device or other suitable device. Accordingly, duplicate base plugs must typically be provided which are isolated from the accessory while still allowing the parent device to accept power to the base plug or other information for other accessories. This can significantly increase costs and device complexity.
Other solutions have been to provide smart batteries having card reader capabilities. For example, some cell phones have subscriber identity modules (SIMs) which can be slipped into a battery slot. The battery contains an electrical circuit that can read the SIM and provide information to the accessory device. In addition, card reading circuitry is also integrated into the battery. However, such devices typically employ an additional battery within the accessory device and are typically integrated into an integral module that requires a user to purchase a new accessory device when the battery of the accessory device needs to be replaced. In addition, another battery is typically required for normal operation of the phone when the accessory is removed. This can unnecessarily increase the cost and complexity of the system. In addition, such systems typically employ connectors that use the same electrical contacts for the accessory as were used for the parent circuits. For example, a SIM may be removed as part of the phone and placed as a plug-in SIM as part of the accessory. The existing SIM contacts in the parent device are used to connect with a multiplexing circuit within the accessory (e.g., smart battery) to allow both the SIM and an accessory to be multiplexed to the parent devices SIM contact block. However, such devices can be quite costly and complex.
Other cell phones are known which allow battery modules, with integral batteries, to be interconnected with a parent housing and/or accessories through two rows of stacked contacts. The two rows of stacked contacts are typically offset in height so that, depending upon the type of accessory, different contacts are utilized. Such stacked contacts are typically arranged such that the resiliency of the contacts from the phone body with the battery module typically act to force the battery module away from the phone body. This can result in increased gaps between the battery and the device. For example, such phones with two rows of stacked contacts typically have their two rows of contacts located on a back surface and the battery module is slid into place so that compliant contacts of the battery module contact with non-compliant stacked contacts coming out of the phone body. Moreover, the battery modules do not include removable battery covers and require a user to purchase an entire battery module if the battery needs to be replaced.
Consequently, a need exists for an improved electrical connector, removable battery cover and electronic appliance which attempts to overcome the above problems.